The responses of the insect immune system to vertebrate parasites and pathogens is an important factor in determming whether or not an insect species is able to transmit human disease. Although cellular immune responses to Plasmodia and filarial worn's are evident and can limit disease transmission, the role of the insect immune system in limiting virus transmission is not well understood. The vertebrate immune system mounts vigorous responses to both viral and eukryotic pathogens that can limit disease transmission. The insect immune system has many similarities with vertebrate innate immunity employing interactive cellular and humoral responses to eliminate infectious nonself materials. Our studies of an unusual insect virus that suppresses the immune system responses to eukaryotic and viral agents suggest that cellular and humoral immunity are disrupted by the virus in largely independent processes. That is some viral genes that suppress cellular immune responses have little effect on the humoral immunity and conversely, treatments that innibit the humoral immune response do not necessarily block cellular immunity. We propose to clarify these apparently independent mechanisms of suppressing insect immune responses to infection, associate cloned viral genes with suppression of cellular and humoral immunity and manipulate the cellular and humoraLimmune responses independently to elucidate the respective roles of cellular and humoral immunity in limiting infections of parasitic and viral agents in insects. These studies will clarify the respective roles of cellular and humoral immunity in limiting infections by eukaryotic and viral parasites of insects.